What are tracking cookies?

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With web browsers playing an ever more central role in our use of computers, and even becoming the only way to interact with a machine (if Chrome OS gets popular), the subject of privacy keeps coming up. And with privacy comes along the topic of how we are tracked on the web, often through the use of tracking cookies.

Whenever you visit a website, search the web, or use a social network, data can be logged and kept on record for months or even years about your browsing habits. Over time that data builds up and can be sold on to advertisers or used to form a very accurate profile of individuals.

One of the main ways data is collected is through tracking cookies, but what exactly are they? How do they work? What can you do to stop being tracked?

What is a tracking cookie?

A cookie is just a very small in terms of physical size on your disc, and is basically a text file. Within that file information is stored that allows a site to remember your preferences, help with automatic logins, store what you have in your shopping cart temporarily, or allow for tracking to be done.

Most of the information stored in a cookie is completely innocent and integral to a modern site working the way you expect. Tracking may also be done innocently with a site that wants to know what a user looks at and what sequence pages are visited so as to learn and improve the experience. But it can also extend past a single site and a cookie may track your entire browsing session.

These so-called “persistent cookies” have quite a simple task. When a user visits a website, the server for that site can detect whether the user has been there before by looking for a cookie it recognizes. If one doesn’t exist then a new cookie is created and an ID is assigned for that user. After that each page the user visits has the URL logged and associated with the ID. That same cookie, depending on how it is setup, can then continue to track where the user goes, even when they leave the site, and feed that information back to the original server.

How do you deal with tracking cookies?

Such tracking is seen as an invasion of privacy and therefore both web browsers and suppliers of security tools have created options to block them or utilities to get rid of them. You may have seen these cookies regularly pop up when doing a spyware scan of your machine and “ad trackers” appear as a threat and get removed. They are the tracking cookies put on your machine by advertisers to track what you do. All you need to do is visit a site with one of their ads on it and a tracking cookie can be created on your PC.

Your first line of defense against being tracked in this way is the privacy options available in your web browser. It’s possible to stop cookies being accepted from some or all sites. For example, in Firefox you can go to Tools > Options and select the Privacy tab. In there you will see the following cookie options highlighted by a red box in the image below:

Blocking cookies just requires unticking the two options for accepting cookies from sites and third-party cookies. Other browsers will have similar options to customize cookie use.

The trade-off for doing this is some of your logins won’t be remembered between browsing sessions, but that can be rectified by using a browser plug-in that remembers login details for specific sites securely. It’s best to experiment with the settings and turn off third-party cookies first then all cookies if you can cope without them. Some sites will even inform you they can’t perform properly without cookies being enabled, so you need to test and see what works for you. Enabling cookies is as easy as returning to the Privacy tab rechecking the cookies box, though you can still add exceptions to specific sites.

If you want a utility to remove tracking cookies from your PC there are a lot of choices with many of the tools being completely free to use. To name a few I have successfully used SuperAntiSpyware, MalwareBytes Anti-Malware, Ad-Aware, and Spyware Doctor, all of which did a good job. There are many more available and if you already use a security suite chances are a scan will remove trackers as part of the process.

Further Reading

If you want to learn more about tracking and cookies in general then Wikipedia has a great breakdown of the different types of cookie. Microsoft has a support page telling you how to remove cookies in Internet Explorer, as does Google for the Chrome browser, and Opera for its Opera browser.

If you don’t currently run security software on your machine then you are leaving yourself open to infection as well as tracking. It’s mandatory to run some form of protection on your machine and our sister site PCMag has a great review of the Best Antivirus Software in 2011 to help you decide what to use.